And yet come this fall, or perhaps just in time for Christmas, federal agencies might once again send their nonessential employees home and national parks and museums might close their doors—all because of President Trump’s insistence that Congress fork over about $1.6 billion in seed money for his long-promised southern border wall.

Washington has been warily girding for a wall brawl for months, ever since Trump reluctantly signed a spending bill without the funding in May after Republicans made clear they were unwilling to fight for the project so early in his presidency. And on Tuesday night, in the middle of his defiant, rambling speech in Phoenix, Trump scratched a line in the Arizona clay that just about everyone knew was coming. “Believe me,” he said, “if we have to close down our government, we’re building that wall.”

If Trump had his party fully behind him, you’d expect to see a cavalcade of Republicans running to the cameras the next day, each vowing to do battle on the president’s behalf. But that’s not what happened on Wednesday.

“I don’t think anyone’s interested in having a shutdown. I don’t think it’s in our interest to do so,” House Speaker Paul Ryan told reporters in Oregon, where he was stumping for the legislative agenda item he prizes far more than the wall: tax reform. Another senior House Republican, Representative Tom Cole of Oklahoma, told CNN it would be “a mistake” to shut down the government and a reflection of political “dysfunction” on the part of a party entrusted with control of both Congress and the White House.

Senate Majority Leader Mitch McConnell, whose relationship with Trump has, according to TheNew York Times, disintegrated in recent weeks, issued a bland statement saying that he and the president were still working to advance “their shared goals.” He listed half a dozen of them, but a border wall didn’t make the cut.

With Republicans offering little cover to the president, Democrats dug in even deeper. House Minority Leader Nancy Pelosi characterized a border wall as “immoral” and accused Trump of threatening to “purposefully hurt American communities to force American taxpayers to fund an immoral, ineffective and expensive border wall.” Senate Minority Leader Charles Schumer has even more leverage, since Republicans would need the support of at least eight Democrats to overcome a filibuster of a spending bill that included money for the wall. “If the president pursues this path, against the wishes of both Republicans and Democrats, as well as the majority of the American people, he will be heading towards a government shutdown which nobody will like and which won’t accomplish anything,” Schumer said.

House Republicans last month passed an appropriations bill that included $1.6 billion toward construction of the border wall, but that measure is seen as a non-starter in the Senate, and not just among Democrats. Republicans like Senator Jeff Flake of Arizona, a recent Trump target, have said they’d only support the project if Mexico paid for it as the president repeatedly promised on the campaign trail.

Wall funding would be part of an omnibus appropriations bill, but Congress might not get around to writing one until the end of the year, just before lawmakers head home for the holidays. The House and Senate must pass a spending bill by September 30 to avoid a shutdown, but Ryan on Wednesday all but guaranteed that measure would be a stopgap bill known as a continuing resolution and as such, unlikely to include money for the border wall. “We’re going to need more time to complete our appropriations process, particularly in the Senate,” Ryan said. The speaker said he supported funding for “a physical barrier” along the border, but he expressed little urgency in approving the money quickly.

Even fervent supporters of the project in the House were unwilling to predict the showdown Trump is looking for. “I don’t think anybody wants to shut down government, and I don’t think leadership has the appetite to shut down government,” Representative Andy Biggs of Arizona told me on Wednesday after attending the president’s speech in Phoenix. “I do believe that my constituency expects me to fight for funding for that border fence with the strongest leverage and tools that I have available,” he added.

Biggs is a freshman lawmaker who represents an Arizona district that does not include the border, but he grew up in the southern part of the state and said a wall was “essential in my world.” He’s also a member of the House Freedom Caucus, which has in recent days ramped up its push for the border wall in line with Trump’s request. Still, Biggs said he didn’t yet know what he would do if Ryan asked for his vote on a spending bill that did not include wall funding, if the consequence of failure was a government shutdown. “It’s hard for me to say that I would foreclose funding for certain military obligations and certain essential and necessary services,” he told me. “I’m taking a wait-and-see attitude on that.”

The question is, how much patience does the president have left? Trump has already swallowed one defeat on the border wall, and his evident frustration with both parties in Congress is growing by the day. His souring relationship with Republicans on Capitol Hill raises a possibility that would previously have been unthinkable: If the Republican-led House and Senate sent him legislation at the deadline without his border wall money, would he veto it and cause a shutdown?

Democrats were at a similar loss for predictions on Wednesday. “We’ll get ourselves into trouble if we try to read the president’s mind,” a senior Democratic congressional aide told me. “He’s broken pledges and flip-flopped before.” But, the aide added, “He’s also done insane things before.”

Having already notched a win on the issue this spring, Democrats believe they have the political advantage. Republicans are divided on the wall and many aren’t prioritizing it as much as Trump. And both parties believe Republicans would take the blame for a shutdown that occurred entirely on their watch, especially after polls showed that voters faulted the GOP for the last shutdown under divided government in 2013. Democrats have also shown little interest in a deal that the White House reportedly is considering, in which Trump would back protections for Dreamers in exchange for Democratic support for a host of immigration restrictions and the border wall. The president has also demonstrated a penchant for bluffing, having taking a hard line on the wall earlier this year only to back down—though not before tweeting in May that the government “needs a good ‘shutdown’ in September to fix mess!”

With Congress’ September agenda already filling up—they must raise the debt ceiling and reauthorize several expiring programs—Republicans could implore Trump to keep the government open and put off the border-wall battle for a few more months. But for a president still searching for a legislative trophy, this is a fight that can be delayed only so long, as both parties are beginning to recognize. “It’s the mess that the fall will be,” Biggs said with a knowing chuckle.

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Russell Berman is a staff writer at The Atlantic, where he covers politics.